Leeks are a perennial even though they are usually grown as an annual. They need a fairly long growing season requiring a minimum of 80 days for fast growing varieties (such as Columbus and Varna) and 120 to even 150 days for other popular varieties that may be sweeter or milder (such as Titan or Giant Musselburgh). Probably the most popular variety is King Richard, which has a 75-80 day growing time. Early spring is the best time to plant leeks. I have more success planting little transplants in the garden than I do when sowing seeds but your mileage may vary. If you decide to sow yours from seeds, start the seeds indoors in March and transplant the starts out in the garden in late April. If you decide to set out transplants, look for them in the outdoor garden department in your local Home Depot in late March or early April. Planting the outdoors by the end of April should give the plants ample time to mature by the end of summer. Enjoy!